Ceramics-Silikáty 39 (2) 69-72 (1995)

WETNESS EFFECT ON EPR Cu(II) SPIN LABEL IN HEAT TREATED SILICA XEROGELS

M.Liška, M. Mazúr, H. Hulínová, P. Pelikán, M. Valko, I. Nerád 

The present paper deals with drying of SiO₂ xerogel that leads to the decrease of the intensity of Cu(ll) spin probe EPR signal and to the signa/noise ratio as well. This effect is explained by changes of Cu(II) coordination into an EPR less sensitive one. During a sample dehydration the decrease of electric permittivity causes the increase of the dipole interaction between Cu(II) coordination polyhedral, which plays an important role in decreasing EPR signal.